The present subject matter generally concerns voltage acquisition technology that can be utilized to measure voltage signals into an electrical service (with the present subject matter adapted for either single phase or multi-phase, as determined by a user's needs). More particularly, the subject voltage acquisition technology corresponds to non-active current transformers that provide effective voltage sensing over a wide input voltage range. Different embodiments and aspects of the present subject matter may equally take the form of either apparatus or methodology.
Utility providers employ various meters and corresponding measurement circuitry to monitor the amount of electrical energy generated by or distributed to various service locations. Such locations may be respectively characterized by one of many different single-phase or polyphase service types, corresponding to such common metering voltages as 120, 240, 277 and 480 volts. Some conventional electricity meters have been designed to function at all of these common metering voltages, thus operable over a wide input voltage range. Due to industry standards that often require meter accuracy at a range from about twenty percent below the minimum metered voltage value to about twenty percent above the maximum metered voltage value, meters operable in a full wide input voltage range correspond to those that are fully functional in an overall dynamic range of about 96 volts–576 volts.
Electricity meters typically include some sort of input circuitry for receiving voltage and current signals at the electrical service. Input circuitry for receiving the electrical service current signals is referred to herein as current acquisition circuitry, while input circuitry for receiving the electrical service voltage signals is referred to as voltage acquisition circuitry.
Many different components have conventionally been used in meter voltage acquisition circuitry, including respective voltage transformer, active current transformer, and resistive voltage divider configurations. Voltage transformer configurations utilized to measure the voltage for an electrical service are typically only able to measure at one voltage level, and not over the dynamic range of 96–576 volts. Known voltage acquisition circuitry that utilizes active current transformers require at least three windings to accurately measure voltage signals over a dynamic input voltage range. Both such known exemplary voltage acquisition circuitry configurations may also be relatively large and expensive, thus making them impractical for some electric utility meter embodiments. Additional aspects of instrument transformers, including voltage and current transformers as conventionally utilized in electricity metering applications, are disclosed in pages 273–362 of Handbook for Electricity Metering, Ninth Edition, © 1992 by Edison Electric Institute, which is incorporated herein by reference for all purposes.
As such, it is desired to provide voltage acquisition circuitry within feasible size and cost constraints, while also being fully operable over a wide input voltage range. While various aspects and alternative embodiments may be known in the field of electricity metering, no one design has emerged that generally encompasses the above-referenced characteristics and other desirable features associated voltage acquisition in an electrical service and associated metering technology.